Constant tension winding mechanism



March 3, 1970 D. F. ROLLER 3,498,560

CONSTANT TENSION WINDING MECHANISM Filed Aug. 21, 1988 INVENTOR DAVID F. ROLLER swam-1i ATTORN EY United States Patent O 3,498,560 CONSTANT TENSION WINDING MECHANISM David F. Roller, Elk Grove Village, 11]., assignor to Teletype Corporation, Skokie, 111., a corporation of Delaware Filed Aug. 21, 1968, Ser. No. 754,439 Int. Cl. B65h 77/00 US. Cl. 24275.1 5 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION It is desirable to wind materials onto reels under con stant tension because constant tension winding assures both that the material will be wound uniformly and that excessive forces will not be applied to the material as it enters the reel. Constant tension winding cannot be accomplished by merely rotating winding reels with a constant torque power source since the lever arm through which the winding torque is applied to the material being wound varies directly with the diameter of the roll of material previously wound onto the reel, Threfore, a need exists for a winding mechanism in which the torque applied to a winding reel is continuously varied in accord ance with the diameter of the roll of material on the reel,

SUMMARY OF THE INVENTION In the preferred embodiment a constant tension winding mechanism is comprised of a winding reel, a source of power for rotating the reel, a variable torque coupling for connecting the power source to the reel and means for varying the torque transferred by the coupling from the source to the reel directly with the amount of material on the reel.

DESCRIPTION OF THE DRAWING A more complete understanding of the invention may be had by referring to the following detailed description when taken in conjunction with the drawing wherein:

FIGURE 1 is a side View of a winding mechanism employing the present invention in which certain parts have been broken away more clearly to illustrate certain features of the invention, and

FIGURE 2 is a partial sectional view of the device shown in FIGURE 1 taken generally along the line 2-2 in FIGURE 1 in the direction of the arrows.

DETAILED DESCRIPTION Referring now to the drawing wherein like reference numerals designate like parts throughout the several views and referring particularly to FIGURE 1 thereof, there is shown a roll winding mechanism including a frame 11 which serves to support the various components of the mechanism. The frame 11 is comprised of a rear plate 12, a bottom plate 13 and a front plate 14 which is not shown in FIGURE 1 but which is identical to the rear plate 12.

Power is supplied to the winding mechanism 10 by a motor (not shown) that drives a shaft 20 which is rotatably supported in the rear plate 12 and which has a drive pulley 21 fixed to it. A shaft 25 extends between 3,498,560 Patented Mar. 3, 1970 the rear plate 12 and the front plate 14 and serves to rotatably support a reel drive roller assembly 26. As is most clearly shown in FIGURE 2, the drive roller assembly 26 includes a rotatable reduced reel driving element or portion 27, a pair of reel locating flanges 28 and 29 and a belt receiving pulley 30 formed on the flange 29.

The shaft 25 also pivotally supports a bell crank assembly 34. The assembly 34 includes a lower arm 35 which rotatably supports an idler or driveable pulley 36 having a belt receiving groove 37 formed in it and an upper arm 38 having a tape engaging portion or sensor 39 formed on its distal end.

Referring again to FIGURE 1, there is shown a stub shaft 42 which extends from the front plate 14 to a point whereat it overlies the belt receiving pulley 30. The shaft 42 rotatably supports a guide member deflecting pulley 43 which has a belt receiving groove (not shown) sim ilar to the groove 37 of the pulley 36 formed in it. A pair of shafts 44 and 45 extend between the rear plate 12 and the front plate 14 and serve to rotatably support a pair of reel supporting rollers 46 and 47. The winding mechanism 10 is completed by a drive or torque transmitting endless belt 48 which is operably entrained about pulley 21 and pulley 36 and extends about pulley 30. The latter is disposed within the loop formed by said belt and between pulleys 21 and 36 at any condition of pulley 36; and it is spaced a short distance from pulley 43 between which and pulley 30 the belt passes.

In use, sensor 39 is raised and a tape reel R which may be one of any of the well known types is placed in the winding mechanism 10. When properly positioned in the winding mechanism 10 the reel R is rotatably supported on the rollers 46 and 47 in engagement with the reel driving element 27 of the drive roller assembly 26. The leading end of a length of tape or web T to be coiled into a roll on the reel R is then engaged with the reel R either automatically or manually. When the reel R is properly positioned in the winding mechanism 10 and the leading end of a tape to be wound is engaged with the reel R sensor 39.is lowered into engagement with the center hub portion of the reel R.

After the reel R is properly positioned in the winding mechanism 10 with sensor 39 in engagement with the hub thereof, the motor connected to the shaft 20 is started. Rotationof the shaft 20 causes the pulley 21 to rotate which in turn causes the belt 48 to travel around its course. Since the belt 48 is in engagement with the pulley 30 of the roller drive assembly 26, movement of the belt 48 causes the assembly 26 to rotate. Since the reel R is engaged with the reel driving portion 27 of the assembly 26, this in turn causes rotation of the reel R which causes the tape to be wound onto the reel.

In the event the device which is supplying tape to the reel R temporarily stops supplying tape slippage occurs between the belt 48 and the pulley 30 of the assembly 26 so that the reel R becomes effectively disengaged from the shaft 20 and the motor that is rotating the shaft. Thus, the belt 48 and the pulley 30 act as a clutch for limiting the amount of torque that is transferred from the shaft 20 to the reel R.

As the reel R is rotated a roll of tape T is accumulated on the reel R. Sensor 39 of the bell crank assembly 34 is positioned in engagement with the hub portion of the reel R and, accordingly, as the roll of tape T accumulates the tape engaging portion moves upwardly toward the dashed line position shown in FIGURE 1 thereby rotating the bell crank assembly 34 counterclockwise about the shaft 25. This action causes the lower arm 35 of the bell crank assembly 34 and the driven pulley 36 carried thereon to move counterclockwise about the shaft 25 toward the dashed line position which in turn causes more of the belt 48 to be wrapped about the pulley 30 of the drive roller assembly 26. The amount of torque that is transmitted from belt 48 to pulley 30 is directly proportional to the amount of wrap of the belt about the pulley. The position and geometry of the movable elements of the crank assembly 34, particularly the length of lever arm 38 and the position and length of arm 35 are selected such that the angle of wrap of belt 48 about the reel-driving pulley 30 increases directly with the diameter of the roll tape T as pulley 36 pivots counterclockwise in response to pivoting of sensor 39. Thus, the torque applied to reel R will increase directly with the increase of diameter of the roll of tape T as it is wound onto the reel R.

As the bell crank assembly 34 rocks counterclockwise the portion of the belt passing between the idler pulley 36 and the drive pulley 21 is moved into engagement with the deflecting pulley 43. The pulley 43 functions to force the belt 48 to follow such a course that the resultant force applied to the pulley 36 by the tensions of the portions of the belt 48 extending to and from the pulley 36 always passes virtually through the axis of the shaft 25, that is, through the pivotal axis of the bell crank assembly 34. This means that there is virtually no change in the force necessary to rock the bell crank assembly 34 about its pivotal axis regardless of the size of the roll of tape T.

To appreciate why it is necessary to increase the torque applied to the reel R directly with the size of the roll of tape T Wound onto the reel in order to wind tape onto the reel under constant tension it is helpful to examine the forces that are applied to the reel R in the stall condition. The force opposing rotation of the reel R in the stalled condition is equal to the force F being applied by the reel R to the tape being wound times the radius A of the roll of tape T on the reel. The force attempting to rotate the reel, on the other hand, is equal to the radius B of the reel R times the force P being applied to the reel R by the reel driving portion 27 of the assembly 26. In the stalled condition therefore, FA=PB, Thus, if the winding tension F is to be held constant the force P applied to the reel R must vary directly with the radius A of the roll of tape T since the radius B of the reel R is constant. Threfore, by varying the amount of wrap of the belt 48 about the pulley 30 directly with the radius of the roll of tape T on the reel R, the mechanism shown in the drawing accomplishes constant tension tape winding.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing specification it will be understood that the invention is not limited to the specific embodiment shown but is capable of modification, rearrangement and substitution of parts and elements without departing from the scope of the invention.

What is claimed is:

1. In a roll winding mechanism wherein the winding means includes a rotatable element for driving a reel about which a web is coiled in a roll and has an adjustable torque transmitted thereto through an endless belt in response to the diameter of said roll, the improvement characterized by: a driveable pulley arranged in driveable association with said belt and mounted for angular movement about said element to adjust the extent of engagement of said element and said belt in response to the diameter of said roll.

2. A combination according to claim 1 further characterized by: means defining an axis of rotation for said element; an arm rockably mounted on said axis defining means, said pulley arranged from said arm for rocking movement about said axis defining means to adjust the relationship of said belt and said element.

3. A combination according to claim 2 further characterized by means for causing the resultant forces applied to said pulley by said belt to pass through a predetermined point at any roll induced condition of the pulley.

4. A combination according to claim 3 in which the causing means includes a guide member arranged for holding said belt oriented in the same plane at any condition of said pulley.

5. A combination according to claim 1 further characterized by a belt entrained drive pulley spaced from said driveable pulley, said rotatable element being spaced at a fixed position from said drive pulley and disposed within said belt in driveable association therewith between said pulleys.

References Cited UNITED STATES PATENTS 2,67(),907 3/1954 Huck 24275.1 2,916,227 12/1959 Bowen 24275.5 2,986,353 5/1961 McCoy 24245 3,243,138 3/1966 NilSSOn 242-7545 NATHAN L. MINTZ, Primary Examiner 

